1. Field of the Invention
This invention relates generally to water filtration, and, more specifically, to small-sized water filters with high filtration performance.
2. Description of the Related Art
Unwanted and potentially harmful contamination in water, especially drinking water, is of concern to many people. This concern creates a desire for water treatment devices in the home and elsewhere. Many water treatment devices and methods have been developed to remove or neutralize particulate and chemical contaminants.
Major categories of consumer water filtration systems include plumbed-in or faucet-mount systems that rely on the pressure of the water supply to force untreated water through a water treatment device and non-plumbed, pour-though or batch systems that rely on gravity to move water from an upper influent water chamber, through a filtering means, to a lower effluent water chamber. In general, most pour-through systems use water filters made of loose filtration media, as the force of gravity is not usually enough to push water through more compacted media. On the other hand, most systems that are plumbed into a water line or mounted onto a faucet filter water through porous composite blocks made from filtration media and binders. Water is driven through the block by pressure in the water supply line. Water treatment systems that can use porous composite blocks include under-the-sink, faucet-mount, and refrigerator systems, among others.
One measure of the effectiveness of water treatment relates to adsorption of impurities from the water by the filtration media. One factor that influences the adsorption of impurities is the length of time the water is in contact with the filtration media. In general, the longer the contact time, the more impurities can be adsorbed from the water. On the other hand, even if slowing the flow rate of the water increases the contact time, it is undesirable, for example, for a normally robust faucet water stream to slow to a trickle in order to provide effective water treatment. Mitigating these competing concerns has resulted in large porous composite carbon blocks for faucet-mount water treatment systems. The water can move through the filter at an acceptable rate but has enough contact time with the treatment media because of the length of the path therethrough to provide effective impurity removal.
Whereas a typical faucet is slim and unobtrusive in design, a faucet-mount filtration system attached to a faucet outlet adds considerable bulk because of the size of the porous composite filter block. The large size limits use of these systems as it limits places where they can fit easily. Currently, typical porous composite carbon blocks for faucet-mount water treatment systems as manufactured by Brita® and by PUR® are between 120 and 130 cm3 in size. If the porous composite carbon blocks could be made smaller and maintain or improve their performance, they would be less obtrusive and could be used in more places, such as inside a faucet or on smaller faucets or appliances where currently their bulk could cause an unacceptable mechanical strain. Smaller water filters made of loose filtration media could also be used in applications where filters of conventional size are too large, such as in portable drinking systems.
Accordingly, there is a need for water treatment devices that are small in size and can still meet acceptable standards for contaminant removal.